diff options
author | Richard Smith <richard-llvm@metafoo.co.uk> | 2017-08-08 19:12:28 +0000 |
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committer | Richard Smith <richard-llvm@metafoo.co.uk> | 2017-08-08 19:12:28 +0000 |
commit | 34b5db131b474135574bd12643339a8974077a38 (patch) | |
tree | a63676813c02d003f17e48ab254454d10060ca99 /lib/CodeGen/CGCXXABI.cpp | |
parent | 89be37b467850bf7c86dfe227352f09721092385 (diff) |
PR19668, PR23034: Fix handling of move constructors and deleted copy
constructors when deciding whether classes should be passed indirectly.
This fixes ABI differences between Clang and GCC:
* Previously, Clang ignored the move constructor when making this
determination. It now takes the move constructor into account, per
https://github.com/itanium-cxx-abi/cxx-abi/pull/17 (this change may
seem recent, but the ABI change was agreed on the Itanium C++ ABI
list a long time ago).
* Previously, Clang's behavior when the copy constructor was deleted
was unstable -- depending on whether the lazy declaration of the
copy constructor had been triggered, you might get different behavior.
We now eagerly declare the copy constructor whenever its deletedness
is unclear, and ignore deleted copy/move constructors when looking for
a trivial such constructor.
This also fixes an ABI difference between Clang and MSVC:
* If the copy constructor would be implicitly deleted (but has not been
lazily declared yet), for instance because the class has an rvalue
reference member, we would pass it directly. We now pass such a class
indirectly, matching MSVC.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310401 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/CGCXXABI.cpp')
-rw-r--r-- | lib/CodeGen/CGCXXABI.cpp | 31 |
1 files changed, 1 insertions, 30 deletions
diff --git a/lib/CodeGen/CGCXXABI.cpp b/lib/CodeGen/CGCXXABI.cpp index e29e525edd..033258643d 100644 --- a/lib/CodeGen/CGCXXABI.cpp +++ b/lib/CodeGen/CGCXXABI.cpp @@ -30,38 +30,9 @@ void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) { } bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const { - // If RD has a non-trivial move or copy constructor, we cannot copy the - // argument. - if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor()) - return false; - - // If RD has a non-trivial destructor, we cannot copy the argument. - if (RD->hasNonTrivialDestructor()) - return false; - // We can only copy the argument if there exists at least one trivial, // non-deleted copy or move constructor. - // FIXME: This assumes that all lazily declared copy and move constructors are - // not deleted. This assumption might not be true in some corner cases. - bool CopyDeleted = false; - bool MoveDeleted = false; - for (const CXXConstructorDecl *CD : RD->ctors()) { - if (CD->isCopyConstructor() || CD->isMoveConstructor()) { - assert(CD->isTrivial()); - // We had at least one undeleted trivial copy or move ctor. Return - // directly. - if (!CD->isDeleted()) - return true; - if (CD->isCopyConstructor()) - CopyDeleted = true; - else - MoveDeleted = true; - } - } - - // If all trivial copy and move constructors are deleted, we cannot copy the - // argument. - return !(CopyDeleted && MoveDeleted); + return RD->canPassInRegisters(); } llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) { |